Cable interface for a field device, and field device

Abstract

The invention relates to a cable interface for connecting structurally separate electronics assemblies of a field device, comprising: cables (K, K') having a contact region (KB); contact pins (S) having a contact region (SB); printed circuit board (L) having a cable connection region (KA) and a contact pin connection region (SA); the cables (K, K') are arranged at the cable connection region (KA); the cable connection region (KA) is connected to contact regions (KB) by means of a cable connection; the contact pins (S) are arranged at a distance from one another at the contact pin connection region (SA), the contact pin connection region (SA) is connected to contact regions (SB); a contact pin (S) is assigned to each cable (K, K'); conductor tracks (LB) on the printed circuit board (L) connect contact regions (KB) to contact regions (SB) in an electrically conductive manner; the printed circuit board (L) is arranged in the main body (G); the cables (K, K') and contact pins (S) connected to the printed circuit board (L) are arranged in openings (O1, O2) of the main body (G); a sealing body (D) is integrally connected to the printed circuit board (L), the main body (G), and the cables (K, K') and transmits a tensile force acting on the cables (K, K') to the sealing body (D).

Description

[0001] Cable interface for a field device and field device

[0002] The invention relates to a cable interface between two electronic assemblies of a field device and a field device with a cable interface according to the invention.

[0003] Field devices are particularly widespread and well-known in process measurement technology, for example, for monitoring processes in the chemical industry or in flowing or standing water. Magnetic-inductive flowmeters, for instance, utilize the principle of electrodynamic induction for volumetric flow measurement and are described in numerous publications. Charge carriers of the medium moving perpendicular to a magnetic field induce a measuring voltage in measuring electrodes arranged essentially perpendicular to the flow direction of the medium and perpendicular to the direction of the magnetic field. The measuring voltage induced in the measuring electrodes is proportional to the flow velocity of the medium averaged over the cross-section of the measuring tube, i.e., proportional to the volumetric flow rate. If the density of the medium is known, the mass flow rate in the pipeline or measuring tube can be determined.The measuring voltage is usually tapped via a sensor which is arranged in the area of ​​maximum magnetic field strength with respect to the coordinate along the measuring tube axis and where the maximum measuring voltage is consequently to be expected.

[0004] The sensors of a field device measure the properties of the medium under investigation and are connected to a remotely located process control center. To operate such a sensor, an explosion-proof housing containing one or more electronic modules is mounted on a sensor unit. The electronic module includes, among other things, a measuring amplifier, which is responsible for controlling the sensor and evaluating the signals it outputs. This measuring amplifier is connected to the sensor unit via several cable interfaces.

[0005] For mechanical connection, the explosion-proof housing features a bracket that supports a circuit board to which the measuring amplifier is mounted. The electrical connection runs from the sensor, which is connected by cables, to a cable gland integrated into the sensor unit housing. The cables coming from the sensor are soldered to one side of the gland, while on the other side, cables leading to the measuring amplifier are also soldered to the gland. The cables leading to the measuring amplifier are soldered to another explosion-proof gland, which forms the end of the explosion-proof housing. On the opposite side of this gland, cables are routed directly to the measuring amplifier and then connected to it via a plug.Such an electrical connection is not only very complex in terms of design and therefore very expensive, but also requires a high manufacturing effort.

[0006] Document DE102012108415A1 teaches a cable interface between a sensor unit and an explosion-proof housing, in particular a cable interface between a sensor unit and an explosion-proof housing which enables a simple mechanical and electrical connection.

[0007] In this simplified interface, the measuring amplifier is directly connected to the sensor unit via a single electrical and mechanical connection. The plug-in unit is an integral part of the sensor unit and also serves as its closure. Reducing the number of electrical interfaces improves signal characteristics and enables a more compact device design.

[0008] However, to shield electromagnetic signals, the conductors are arranged in at least two separate chambers of the connector unit, which necessitates a metallic structure at the interface, thus requiring complex, manual manufacturing. Furthermore, the cable arrangement on the connector unit is fixed by the pin positioning and therefore not optimized to minimize the tensile forces transmitted by the cables when disconnecting the interface. This can damage the cable connections when disconnecting the connector unit.

[0009] The present invention therefore aims to provide a cable interface in which the arrangement of the cables and the arrangement of the pins are independent of each other.

[0010] The invention solves the problem by means of a housing assembly according to independent claim 1.

[0011] The cable interface according to the invention for connecting structurally separate electronic assemblies of a field device comprises several cables, each with a first contact area; several contact pins, each with a second contact area; a printed circuit board with at least one cable connection area and at least one contact pin connection area, wherein the several cables are arranged at the at least one cable connection area by a first arrangement; wherein the at least one cable connection area is connected to the first contact areas of the several cables by means of a cable connection; wherein the several contact pins are spaced apart at the at least one contact pin connection area by a second arrangement; wherein the at least one contact pin connection area is connected to the second contact areas of the several contact pins; wherein at least one connected contact pin is assigned to each connected cable;several conductor tracks arranged on the printed circuit board, wherein the several conductor tracks electrically connect the first contact areas of the several cables connected to the at least one cable connection area with second contact areas of associated contact pins connected to the at least one contact pin connection area; a base body with at least one opening, wherein the printed circuit board is arranged in the base body; wherein the several cables connected to the printed circuit board and the several contact pins connected to the printed circuit board are arranged in the at least one opening; a sealing body, wherein the sealing body is materially bonded to the printed circuit board, the base body, and the several cables, and wherein the sealing body is configured to transmit a tensile force acting on the several cables to the sealing body.

[0012] In a further development of the cable interface according to the invention, the several cables are galvanically conductive, in particular materially bonded, connected to the at least one cable connection area.

[0013] In a further development of the cable interface according to the invention, the several contact pins are galvanically conductive, in particular materially bonded, to the at least one contact pin connection area.

[0014] In a further development of the cable interface according to the invention, at least one of the several contact pins is designed as a contact socket.

[0015] In a further development of the cable interface according to the invention, the first arrangement is designed in a linear configuration. Here, the first contact areas are arranged along a straight line which runs in or parallel to a surface plane of the printed circuit board.

[0016] In a further development of the cable interface according to the invention, the second arrangement is planar. In this arrangement, at least one of the second contact areas is spaced apart from a straight line which runs in or parallel to a surface plane of the printed circuit board, along which line at least two further second contact areas are arranged.

[0017] In a further development of the cable interface according to the invention, the printed circuit board is inserted into the base body, in particular by pressing.

[0018] In a further development of the cable interface according to the invention, one of the at least one cable connection areas and / or one of the at least one contact pin connection areas is arranged on a first side of the printed circuit board; wherein one of the at least one cable connection areas and / or one of the at least one contact pin connection areas is arranged on a second side of the printed circuit board.

[0019] In a further development of the cable interface according to the invention, the sealing body is formed by overmolding the base body, the circuit board, and sections of the connected cables with a block polymer.

[0020] In a further development of the cable interface according to the invention, the sealing body comprises a block polymer, in particular based on polyamide, preferably a thermoplastic polyether polyamide.

[0021] In a further development of the cable interface according to the invention, the sealing body is waterproof, in particular gas-tight, and preferably a separating element between explosion-proof and non-explosion-proof areas.

[0022] In a further development of the cable interface according to the invention, the base body comprises a plastic, in particular polyphenylene sulfide.

[0023] In a further development of the cable interface according to the invention, the at least one connection of the at least one cable to the circuit board comprises a soldered connection.

[0024] In a further development of the cable interface according to the invention, the circuit board consists of an electrically insulating material, in particular plastic; wherein the conductor tracks consist of an electrically conductive material, in particular copper or aluminum.

[0025] In a further development of the cable interface according to the invention, the printed circuit board comprises at least one electronic element; wherein the at least one electronic element is electrically connected to at least one conductor track.

[0026] The field device for measurement and automation technology according to the invention comprises a cable interface according to the invention or a further development of the cable interface according to the invention. Furthermore, the field device comprises two structurally separate electronic assemblies.

[0027] In a further development of the field device according to the invention, it comprises at least two housing assemblies, each with a cable guide; wherein each of the two electronic assemblies is arranged in a separate housing assembly; wherein the cables of the cable interface are arranged in the cable guide. The invention has the advantage that the cable interface can be realized without an internal shield against electric and magnetic fields and without conductive fillers forming an internal structure, which opens up a multitude of design and manufacturing possibilities, increases process reliability, and reduces manufacturing costs.

[0028] Furthermore, the use of a printed circuit board to connect contact pins and cables offers the advantage of automated manufacturing / assembly.

[0029] Furthermore, the advantage is that no additional insulators are necessary due to the fact that the base body is made of plastic.

[0030] Furthermore, the base body can be made of heat-resistant plastics, such as PPS, to meet process requirements. Another advantage is that the sealing element can be manufactured by overmolding the circuit board, cables, contact pins, and base body, thus protecting the electrical connections, particularly against corrosion.

[0031] Furthermore, there is the advantage that the connection between cable and circuit board or contact pins and circuit board is strain-relieved, especially since a pull on the cables exerts a force on the base body, which force can be transferred at least in part by the sealing body.

[0032] Furthermore, there is the advantage that additional electronic components can be arranged on the circuit board, for example to process, amplify or attenuate signals transmitted via cables.

[0033] Furthermore, the advantage is that the cable interface according to the invention can be used to connect a remote sensor to a field device, whereby the connector with long cables can be connected to both the field device and the sensor.

[0034] Furthermore, the advantage is that two or more cable interfaces according to the invention can be connected to each other with suitable contact sockets in order to realize an extension of the interface according to the invention, which is, for example, waterproof and connectable.

[0035] The invention is explained using the following figures. It shows:

[0036] Fig. 1 shows an embodiment of the populated circuit board according to the invention;

[0037] Fig. 2 shows an embodiment of the interface according to the invention;

[0038] Fig. 3 shows a cross-section through an embodiment of the interface according to the invention;

[0039] Fig. 4 shows an embodiment of the components of the interface according to the invention;

[0040] Fig. 5 shows a schematic view of an embodiment of the field device according to the invention. The embodiment of the printed circuit board according to the invention shown in Fig. 1 depicts the printed circuit board L equipped with cables K and contact pins S. The cables K and K' transmit electrical currents; cable K' can, for example, be configured to transmit currents, particularly for data transmission, while cable K'' is configured to connect the printed circuit board L to a reference potential. In this embodiment of the printed circuit board according to the invention, cable K' is configured to carry currents for controlling magnetic coils. In an advantageous first arrangement, in this specific embodiment linearly, the cables K, K', and K'' are connected via a cable contact area KB to the cable connection area KA on a first side S1 of the printed circuit board L, in this embodiment by a plug connection.The contact pins S form a group that can be addressed by an electronic assembly as one or more logic channels and can be configured for transmitting current, switching components on or off, and / or transmitting digital information via a communication protocol. The contact pins S are connected via a contact pin contact area SB to the contact pin connection area SA on a second side S2 of the printed circuit board L, in this embodiment by a plug connector. The contact pins are arranged in a second configuration, in this embodiment as a flat surface, to be connected to a matching female part of a plug connector.

[0041] The conductive traces LB arranged on the circuit board L electrically connect the cable contact areas to the contact pin contact areas. The connection of cables K, K' and contact pins S enables the transmission of electrical current and / or digital information.

[0042] The embodiment of the cable interface according to the invention shown in Fig. 2 depicts the base body G, in this specific case made of the plastic PPS, into which the populated circuit board L (not visible in this illustration) is pressed, so that the cables K, K', K" protrude through the first opening 01, while the contact pins KS (not visible in this illustration) protrude through the second opening 02. The sealing element D is formed by overmolding the (here not visible) circuit board L, the cables K, K', K" and sections of the base body G with a plastic, in this embodiment with thermoplastic polyether polyamide. The sealing element D covers and protects the circuit board L, the conductor tracks LB, the cable contact areas, and seals the electrical connection against environmental influences.

[0043] The cross-section of an embodiment of the cable interface according to the invention, shown in Fig. 3, depicts the base body G into which the populated circuit board L is pressed, such that the cables K, K', K" protrude through the first opening 01, while the contact pins S protrude through the second opening 02. The sealing body D encloses the circuit board L, the cables K, K', K" and sections of the base body G. The sealing body D covers and protects the circuit board L, the conductor tracks LB (not shown here), the cable contact areas, and seals the electrical connection against environmental influences, in particular against water and gas.

[0044] The embodiments of the components of the cable interface according to the invention shown in Fig. 4 comprise a view of a first side S1 of the base body G with opening 01, a view of a second side S2 of the base body G with opening 02, a view of the circuit board L with conductor tracks LB, and a contact pin S.

[0045] The schematic view shown in Fig. 5 of an embodiment of the field device according to the invention depicts the two electronic assemblies EB1 and EB2, which can be assigned, for example, to a sensor and a measuring and operating circuit. The electronic assemblies are structurally separated in two housing assemblies GG1 and GG2, each of which has a cable guide KF1 and KF2 in which the cables K are arranged. The cables K are connected to one of the electronic assemblies EB1, and the base body G is electrically connected to the second electronic assembly via the (not visible here) contact pins KS, thereby enabling the exchange of electrical currents and / or digital information between the electronic assemblies EB1 and EB2.

[0046] Reference symbol list

[0047] K, K', K" cable

[0048] KB first contact area

[0049] S contact pins

[0050] SB second contact area

[0051] L circuit board

[0052] 51 first side of the circuit board

[0053] 52 second side of the circuit board

[0054] KA cable connection area

[0055] SA contact pin connection area

[0056] LB conductor tracks

[0057] G Basic body

[0058] 01, 02 Opening

[0059] D Sealing body

[0060] EB1, EB2 electronic assembly

[0061] G1, G2 Housing assembly

[0062] KF1, KF2 cable routing

[0063] E Electronic element

Claims

Patent claims 1. Cable interface for connecting structurally separate electronic assemblies of a field device, comprising: • several cables (K, K') each with a first contact area (KB); • several contact pins (S), each with a second contact area (SB); • a printed circuit board (L) with a material thickness between 0.3 and 5 mm and with at least one cable connection area (KA) and at least one contact pin connection area (SA), wherein the multiple cables (K, K') are arranged on the at least one cable connection area (KA) by a first arrangement; wherein the at least one cable connection area (KA) is connected to the first contact areas (KB) of the multiple cables (K, K') by means of a cable connection; wherein the multiple contact pins (S) are spaced apart on the at least one contact pin connection area (SA) by a second arrangement; wherein the at least one contact pin connection area (SA) is connected to the second contact areas (SB) of the multiple contact pins (S); wherein at least one connected contact pin (S) is assigned to each connected cable (K, K'); • several conductor tracks (LB) arranged on the circuit board (L), o wherein the several conductor tracks (LB) electrically connect the first contact areas (KB) of the several cables (K, K') connected to the at least one cable connection area (KA) with second contact areas (SB) of associated contact pins (S) connected to the at least one contact pin connection area (SB); • a base body (G) with at least one opening (01 , 02), o wherein the circuit board (L) is arranged in the base body (G); o wherein the multiple cables (K, K') connected to the circuit board (L) and the multiple contact pins (S) connected to the circuit board (L) are arranged in the at least one opening (01 , 02); • a sealing body (D), o wherein the sealing body (D) is materially bonded to the circuit board (L), the base body (G), and the multiple cables (K, K'), o wherein the sealing body (D) is configured to transmit a tensile force acting on the multiple cables (K, K') to the sealing body (D); 2. Cable interface according to claim 1, • wherein the multiple cables (K, K') are galvanically conductive, in particular materially bonded, to the at least one cable connection area (KA).

3. Cable interface according to one of claims 1 or 2, • wherein the multiple contact pins (S) are galvanically conductive, in particular materially bonded, to the at least one contact pin connection area (SA).

4. Cable interface according to one of claims 1 to 3, • wherein at least one of the several contact pins (S) is designed as a contact socket.

5. Cable interface according to one of claims 1 to 4, • wherein the first arrangement is linear.

6. Cable interface according to one of claims 1 to 5, • where the second arrangement is planar.

7. Cable interface according to one of claims 1 to 6, • wherein the printed circuit board (L) is inserted into the base body (G), in particular by pressing.

8. Cable interface according to one of claims 1 to 7, • wherein one of the at least one cable connection areas (KA) and / or one of the at least one contact pin connection areas (SA), in particular a cable connection area (KA), is arranged on a first side (S1) of the printed circuit board (L); • wherein one of the at least one cable connection areas (KA) and / or one of the at least one contact pin connection areas (SA), in particular a contact pin connection area (SA), is arranged on a second side (S2) of the printed circuit board (L).

9. Cable interface according to one of claims 1 to 8, • wherein sealing body (D) is formed by overmolding the base body (G), the circuit board (L), and sections of the connected cables (K, K') with a block polymer.

10. Cable interface according to one of claims 1 to 9, • wherein the sealing body (D) comprises a block polymer, in particular based on polyamide, preferably a thermoplastic polyether polyamide.

11. Cable interface according to one of claims 1 to 10, • wherein the sealing body (D) is watertight, in particular gas-tight, and preferably a separating element between explosion-proof and non-explosion-proof areas.

12. Cable interface according to one of claims 1 to 11 , • wherein the base body (G) comprises a plastic, in particular polyphenylene sulfide.

13. Cable interface according to one of claims 1 to 12, • wherein at least one connection of the at least one cable (K, K') to the circuit board (L) comprises a soldered connection.

14. Cable interface according to one of claims 1 to 13, • wherein the circuit board (L) consists of an electrically insulating material, in particular plastic; • wherein the conductor tracks (TR) are made of an electrically conductive material, in particular copper or aluminium.

15. Cable interface according to one of claims 1 to 14, • wherein the printed circuit board (L) comprises at least one electronic element (E); • wherein the at least one electronic element (E) is electrically connected to at least one conductor track (LB).

16. Field device for measurement and automation technology, comprising a cable interface according to one of claims 1 to 15, further comprising: • two structurally separate electronic assemblies (EB1 , EB2).

17. Field device according to claim 16, further comprising: • at least two housing assemblies (G1, G2) each with a cable guide (KF1, KF2); • wherein each of the two electronic assemblies (EB1 , EB2) is arranged in a separate housing assembly (G1 , G2); • wherein the cables (K, K') of the cable interface are arranged in the cable guide (KF1 , KF2).

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